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  Subjects -> ENGINEERING (Total: 2258 journals)
    - CHEMICAL ENGINEERING (189 journals)
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    - ELECTRICAL ENGINEERING (99 journals)
    - ENGINEERING (1197 journals)
    - ENGINEERING MECHANICS AND MATERIALS (388 journals)
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    - MECHANICAL ENGINEERING (89 journals)

CHEMICAL ENGINEERING (189 journals)                     

Showing 1 - 0 of 0 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 5)
ACS Sustainable Chemistry & Engineering     Hybrid Journal   (Followers: 2)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 4)
Acta Polymerica     Hybrid Journal   (Followers: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 6)
Advanced Chemical Engineering Research     Open Access   (Followers: 28)
Advanced Powder Technology     Hybrid Journal   (Followers: 15)
Advances in Applied Ceramics     Hybrid Journal   (Followers: 4)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 23)
Advances in Chemical Engineering and Science     Open Access   (Followers: 52)
Advances in Polymer Technology     Hybrid Journal   (Followers: 12)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 11)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 6)
Applied Petrochemical Research     Open Access   (Followers: 2)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 7)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 14)
Biofuel Research Journal     Open Access   (Followers: 4)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 7)
Catalysts     Open Access   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription  
Chemical and Engineering News     Free   (Followers: 10)
Chemical and Materials Engineering     Open Access   (Followers: 8)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 10)
Chemical and Process Engineering     Open Access   (Followers: 22)
Chemical and Process Engineering Research     Open Access   (Followers: 19)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 32)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 17)
Chemical Engineering and Science     Open Access   (Followers: 14)
Chemical Engineering Communications     Hybrid Journal   (Followers: 12)
Chemical Engineering Journal     Hybrid Journal   (Followers: 30)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 21)
Chemical Engineering Research Bulletin     Open Access   (Followers: 9)
Chemical Engineering Science     Hybrid Journal   (Followers: 21)
Chemical Geology     Hybrid Journal   (Followers: 15)
Chemical Papers     Hybrid Journal   (Followers: 2)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 142)
Chemical Society Reviews     Full-text available via subscription   (Followers: 38)
Chemical Technology     Open Access   (Followers: 12)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry of Materials     Full-text available via subscription   (Followers: 162)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 4)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal   (Followers: 1)
Coloration Technology     Hybrid Journal  
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 1)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
CORROSION     Full-text available via subscription   (Followers: 18)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 33)
Corrosion Reviews     Hybrid Journal   (Followers: 3)
Crystal Research and Technology     Hybrid Journal   (Followers: 5)
Current Opinion in Chemical Engineering     Open Access   (Followers: 7)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription   (Followers: 1)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 4)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Gels     Open Access  
Geochemistry International     Hybrid Journal   (Followers: 2)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 5)
Heat Exchangers     Open Access   (Followers: 2)
High Performance Polymers     Hybrid Journal  
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 5)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 9)
Indonesian Journal of Chemical Science     Open Access   (Followers: 1)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 20)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Gases     Open Access  
Info Chimie Magazine     Full-text available via subscription   (Followers: 3)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 2)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 2)
International Journal of Chemical Technology     Open Access   (Followers: 5)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 3)
International Journal of Industrial Chemistry     Open Access   (Followers: 1)
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 5)
International Journal of Science and Engineering     Open Access   (Followers: 4)
International Journal of Waste Resources     Open Access   (Followers: 3)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 4)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 5)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 11)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 111)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 9)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 6)
Journal of Chemical Engineering     Open Access   (Followers: 15)
Journal of Chemical Engineering and Materials Science     Open Access   (Followers: 2)
Journal of Chemical Science and Technology     Open Access   (Followers: 4)
Journal of Chemical Sciences     Partially Free   (Followers: 17)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 14)
Journal of CO2 Utilization     Hybrid Journal   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 7)
Journal of Environmental Chemical Engineering     Hybrid Journal   (Followers: 3)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Processing & Technology     Open Access  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 4)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 1)
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (Followers: 1)
Journal of Information Display     Hybrid Journal  
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 8)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 5)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 7)
Journal of Organic Semiconductors     Open Access   (Followers: 4)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 5)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 4)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 8)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 5)
Journal of Polymers     Open Access   (Followers: 2)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 266)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Brazilian Chemical Society     Open Access   (Followers: 2)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 1)
Journal of the Pakistan Institute of Chemical Engineers     Open Access   (Followers: 1)
Journal of the Taiwan Institute of Chemical Engineers     Hybrid Journal   (Followers: 2)
Journal of Water Chemistry and Technology     Hybrid Journal   (Followers: 8)
Jurnal Bahan Alam Terbarukan     Open Access  
Jurnal Inovasi Pendidikan Kimia     Open Access  
Jurnal Reaktor     Open Access  
Jurnal Teknologi Dan Industri Pangan     Open Access   (Followers: 1)
Korean Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 1)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 14)
Materials Science and Applied Chemistry     Open Access  
Materials Sciences and Applied Chemistry     Full-text available via subscription  
Modern Chemistry & Applications     Open Access  
Molecular Imprinting     Open Access  
Nanocontainers     Open Access  
Nanofabrication     Open Access  
Noise Control Engineering Journal     Full-text available via subscription   (Followers: 2)
Ochrona Srodowiska i Zasobów Naturalnych : Environmental Protection and Natural Resources     Open Access  
Petroleum Chemistry     Hybrid Journal   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 3)
Plasma Processes and Polymers     Hybrid Journal  
Plasmas and Polymers     Hybrid Journal  
Polymer     Hybrid Journal   (Followers: 118)
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 14)
Polyolefins Journal     Open Access  
Powder Technology     Hybrid Journal   (Followers: 14)
Recyclable Catalysis     Open Access   (Followers: 1)
Research on Chemical Intermediates     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 5)
Revista Colombiana de Ciencias Químico-Farmacéuticas     Open Access  
Revista Cubana de Química     Open Access  
Revista ION     Open Access  
Revista Mexicana de Ingeniería Química     Open Access  
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Bulletin     Hybrid Journal   (Followers: 2)
Russian Journal of Applied Chemistry     Hybrid Journal   (Followers: 1)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 58)
Solid Fuel Chemistry     Hybrid Journal  
South African Journal of Chemical Engineering     Open Access   (Followers: 2)
South African Journal of Chemistry     Open Access   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 5)
Sustainable Chemical Processes     Open Access   (Followers: 2)
Synthesis Lectures on Chemical Engineering and Biochemical Engineering     Full-text available via subscription  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 4)
The Chemical Record     Hybrid Journal   (Followers: 1)
Theoretical Foundations of Chemical Engineering     Hybrid Journal   (Followers: 2)
Transition Metal Chemistry     Hybrid Journal   (Followers: 2)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Visegrad Journal on Bioeconomy and Sustainable Development     Open Access   (Followers: 2)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)

           

Journal Cover Chemical Engineering Science
  [SJR: 1.073]   [H-I: 135]   [21 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [3040 journals]
  • Frequency domain constrained optimization of boundary control action for
           maximization of mixing in channel flow
    • Authors: Pesila Ratnayake; Jie Bao
      Pages: 1 - 20
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Pesila Ratnayake, Jie Bao
      Improving mixing is one of the important goals in flow control, e.g., to decrease concentration polarization in membrane systems to reduce fouling. As with many distributed parameter systems, fluid flow can be controlled using boundary value manipulation. Fluid manipulation using electro-osmosis is studied in this work, where several cylindrical electrodes are used to create multiple spatially non-uniform time-varying electric fields. The proposed approach converts the distributed parameter system into an infinite-dimensional system by spatial and spectral discretization. A virtual output variable is constructed to allow the optimization of a mixing objective function to be conducted using frequency response analysis, with consideration of the constraints of conservation of charge. The solution obtained in this paper is the input profile that provides the greatest achievable ratio of time-average dissipation function to time-average input energy satisfying the input constraints.

      PubDate: 2016-10-04T09:54:44Z
      DOI: 10.1016/j.ces.2016.09.013
      Issue No: Vol. 158 (2016)
       
  • Xylose enhances furfural tolerance in Candida tropicalis by improving NADH
           recycle
    • Authors: Shizeng Wang; Zijun He; Qipeng Yuan
      Pages: 37 - 40
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Shizeng Wang, Zijun He, Qipeng Yuan
      Furfural is one of the typical inhibitors present in hemicellulose hydrolysate. Furfural is harmful to cell growth and biofuel production in microbes. As one of the microbes that could use xylose in hemicellulose hydrolysate, Candia. tropicalis shows a promising potential for metabolic engineering to produce biofuels and value-added chemicals. In this study, we found that the rate of furfural degradation and half maximal inhibitory concentration for furfural of C. tropicalis in xylose medium increased 1.68-fold and 1.19-fold, respectively, compared with those in glucose medium, indicating that C. tropicalis obtained better furfural tolerance in xylose medium. The dehydrogenation of xylitol, which produces coenzyme NADH, promotes the recycle of NAD+ and facilitates the reduction of furfural. This study provides important information for metabolic regulation and metabolic engineering of efficient lignocellulose fermentation strains.
      Graphical abstract image

      PubDate: 2016-10-10T15:18:25Z
      DOI: 10.1016/j.ces.2016.09.026
      Issue No: Vol. 158 (2016)
       
  • The effect of operating conditions on the residence time distribution and
           axial dispersion coefficient of a cohesive powder in a rotary kiln
    • Authors: Ingrid J. Paredes; Bereket Yohannes; Heather Emady; Benjamin J. Glasser; William G. Borghard; Fernando Muzzio; Alberto M. Cuitiño; Jean Beeckman; Samia Ilias; Paul Podsiadlo; Eric Jezek; Joseph Baumgartner
      Pages: 50 - 57
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Ingrid J. Paredes, Bereket Yohannes, Heather Emady, Benjamin J. Glasser, William G. Borghard, Fernando Muzzio, Alberto M. Cuitiño, Jean Beeckman, Samia Ilias, Paul Podsiadlo, Eric Jezek, Joseph Baumgartner
      While continuous rotary calcination is a widely used thermal treatment in large-scale catalyst manufacturing, the process's heat and mass transfer mechanisms remain a challenge to characterize and to predict. Thus, the goal of this research is to improve fundamental understanding of rotary calcination to aid in the creation of a scientific methodology for process design and scale-up. For successful calcination to occur, the residence time of the particles must exceed the time required for heating and calcination at a set temperature. The optimal residence time therefore depends on both of these competing time scales, each of which is function of feed material properties, kiln geometry and kiln operating conditions. For uniform treatment of the feed, the particles must also exhibit low axial dispersion. In this work, the residence time distribution and axial dispersion coefficient for a dry cohesive fluid cracking catalyst powder were measured in a pilot plant kiln using a tracer study developed by Danckwerts. Results were successfully matched to the Taylor fit of the axial dispersion model and the Sullivan prediction for mean residence time. It was found that an increase in feed rate, kiln incline and rotary speed decreased mean residence time and overall axial dispersion. Such results have been established previously for free-flowing material like millimeter-sized extrudates, but have not been previously reported for the cohesive powders such as the one used in our work. As in free-flowing material, the axial dispersion coefficient was found to vary with kiln conditions. The values of the axial dispersion coefficients were lower for the powder than for free-flowing material, showing a dependency of axial dispersion on material properties as well as bulk flow behavior.

      PubDate: 2016-10-16T15:25:41Z
      DOI: 10.1016/j.ces.2016.09.028
      Issue No: Vol. 158 (2016)
       
  • Review of cluster characteristics in circulating fluidized bed (CFB)
           risers
    • Authors: Andy Cahyadi; Aditya Anantharaman; Shiliang Yang; S.B. Reddy Karri; John G. Findlay; Ray A. Cocco; Jia Wei Chew
      Pages: 70 - 95
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Andy Cahyadi, Aditya Anantharaman, Shiliang Yang, S.B. Reddy Karri, John G. Findlay, Ray A. Cocco, Jia Wei Chew
      Particle clusters are well acknowledged to affect the hydrodynamics and overall performance of gas-solid fluidized beds. Since one of the first reports on the clustering phenomenon in 1948, the understanding of particle clustering has been rigorously attempted via both modeling and experimental efforts, with significant traction gained especially in the last few decades. Accordingly, the current review targets at providing a comprehensive landscape of the experimental cluster trends to summarize the findings, in particular on circulating fluidized bed (CFB) risers, to date. More questions than answers seem to have sprouted from the abundant experimental data available, which impedes model development. The quantitative comparison of cluster characteristics across studies must be treated with caution, because of (i) different riser configurations, instruments and analysis methods, which can lead to discrepancies of an order-of-magnitude; (ii) the impact on cluster characteristics by an interplay of a host of factors, hence the influence of a single parameter is not straightforward, even within the same study; (iii) the irregularity in the form of clusters, hence the definition and/or measurement of the various cluster characteristics differ; and (iv) the general lack in the reporting of the actual particle size distribution. What is remarkable is that the trends of the cluster characteristics are relatively consistent despite different experimentalists and units.

      PubDate: 2016-10-16T15:25:41Z
      DOI: 10.1016/j.ces.2016.10.002
      Issue No: Vol. 158 (2016)
       
  • Preparation of a non-hydrothermal NaA zeolite membrane and defect
           elimination by vacuum-inhalation repair method
    • Authors: Meng-xue Xu; Yan He; Yi-pin Wang; Xue-min Cui
      Pages: 117 - 123
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Meng-xue Xu, Yan He, Yi-pin Wang, Xue-min Cui
      This work reports the preparation of a non-hydrothermal NaA zeolite and its stainless steel-supported membrane using geopolymer-gel-thermal-conversion (GGTC) combined with a dip-coating method, which does not require hydrothermal processing. The XRD and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the 1.1Na2O–Al2O3–2SiO2–8H2O geopolymer gels cured at 25°C nucleate in the geopolymerization stage. After heat-treatment above 60°C, the crystal nuclei in the geopolymer gels continue to grow and transform into NaA zeolite crystals with good crystallinity. To improve the separation efficiency of the stainless steel-supported NaA zeolite membrane in the pervaporation (PV) process of an ethanol/water mixture, this paper reports a simple vacuum-inhalation repair method for non-zeolitic pores or other defects in the NaA zeolite membrane. After vacuum-inhalation repair of the non-hydrothermal NaA zeolite membrane with sodium alginate solutions and CaCl2 solutions, in that order, the repaired NaA zeolite membrane exhibited a separation factor that was enhanced approximately 7- to 14-fold over that of the unrepaired NaA zeolite membrane.

      PubDate: 2016-10-16T15:25:41Z
      DOI: 10.1016/j.ces.2016.10.001
      Issue No: Vol. 158 (2016)
       
  • Method of quantifying surface roughness for accurate adhesive force
           predictions
    • Authors: Casey Q. LaMarche; Stuart Leadley; Peiyuan Liu; Kevin M. Kellogg; Christine M. Hrenya
      Pages: 140 - 153
      Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Casey Q. LaMarche, Stuart Leadley, Peiyuan Liu, Kevin M. Kellogg, Christine M. Hrenya
      The van der Waals force between contacting surfaces depends strongly on the surface roughness. Theories that allow for estimating the adhesion force, or the force to separate surfaces from contact, with simple, single-equation theories (i.e., by considering roughness asperities as submerged-spheres) can be easily instituted in discrete element method simulations of many-particle systems, but require inputs that rely on quantification of the surface roughness. In this work, Atomic Force Microscope (AFM) topographical surface maps reveal that two scales of roughness characterize the surfaces of particles examined, similar to prior studies. Previously, the separation of the two roughness scales and determination of the associated wavelength, which are necessary for predicting adhesion forces, relied on visual selection. Here, an objective methodology to separate the scales of surface roughness and calculate the wavelength of each scale is established. Two artifacts are identified when using the new methodology that negatively impact adhesion force predictions if not eliminated, namely the Gibbs artifact and an “atomic-scale-noise” artifact. Procedures to overcome these artifacts are developed. The resulting surface roughness characterizations are employed in a new theory, the predictions of which are in excellent agreement with AFM pull-off force measurements. The new theory extends a current van der Waals theory, which treats surface roughness as submerged spheres, by accounting for two rough surfaces instead of one.
      Graphical abstract image

      PubDate: 2016-10-24T13:30:21Z
      DOI: 10.1016/j.ces.2016.09.024
      Issue No: Vol. 158 (2016)
       
  • Modelling geometrical and fluid-dynamic aspects of a continuous fluidized
           bed crystallizer for separation of enantiomers
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Michael Mangold, Dmytro Khlopov, Erik Temmel, Heike Lorenz, Andreas Seidel-Morgenstern
      Continuous selective crystallization using mixed suspension mixed product removal (MSMPR) crystallizers is an attractive method for separating enantiomers. Recent experimental results confirm the feasibility of the approach, but also indicate that the operation conditions for nominal operation lie in a rather small window. A systematic analysis and an optimal design are needed to exploit the full potential of the method. In this contribution, a mathematical process model based on population balance equations is presented. In contrast to other studies in literature, the considered crystallizer is not a stirred tank, but has a conical shape that requires a spatially distributed model formulation. Parameter studies identify the key operation and design parameters for maximizing the mass of the product crystals and for shaping their size distribution. The proposed model focuses on geometrical and fluid-dynamic aspects, but at the current stage does not include purity aspects.

      PubDate: 2016-12-06T13:10:17Z
       
  • An equilibrium theory for catalytic steam reforming in membrane reactors
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): M.A. Murmura, S. Cerbelli, M.C. Annesini
      The study of integrated membrane reactors for the production of pure hydrogen is attracting increasing interest. In this work, we show how these systems may be described through pure transport models, accounting for the competition between different transport mechanisms, in the limit for either infinitely fast or infinitely slow reaction. The actual performance of a reactor will lie between these two limiting-case conditions. The results of this work highlight that the behavior of these systems may be described as a continuous sequence of equilibrium states. The main novelty of the study is in the introduction of a simple model that allows to evaluate integral quantities, such as hydrogen permeate flow rate and yield, on the basis of physical parameters and not through fitting of transport coefficients. Methane steam reforming has been chosen as a case study, but the conclusions reached may be extended to other integrated reactors for which the permeation law of the product across the membrane is non-linear.

      PubDate: 2016-12-06T13:10:17Z
       
  • Development of electrolyte inhibitors in nickel cadmium batteries
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Kobra Pourabdollah
      The aim of this project was enhancement the stability of alkaline electrolyte in nickel cadmium batteries during unavoidable gradually CO2 absorption from the air. As the most concern of nickel cadmium batteries, CO2 absorption intensifies the electrolyte damage via diverting the hydroxide to the carbonate anions leading to depletion of battery capacity and electrical performance. The objectives of this paper are (1) investigation of novel chemical inhibitors to retard the deleterious CO2 absorption in alkaline electrolytes and (2) development of kinetics and mechanisms to justify their behavior. Some homologues of CO2 absorption inhibitors were experimentally examined at different levels and their reaction kinetics and experimental characteristics were determined. The results revealed that low dosages of such inhibitors in alkaline electrolyte of nickel cadmium batteries declines CO2 absorption and hydroxide consumption (or carbonate formation) and increases the lifetime of both electrolyte and electrodes. The experimental achievements were applied in some blocks of industrial nickel cadmium batteries representing a fantastic inhibition of CO2 absorption in alkaline electrolyte.
      Graphical abstract image

      PubDate: 2016-12-06T13:10:17Z
       
  • An efficient approximate moment method for multi-dimensional population
           balance models – Application to virus replication in multi-cellular
           systems
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Robert Dürr, Thomas Müller, Stefanie Duvigneau, Achim Kienle
      Many particulate processes in process and bioprocess engineering can be described with multi-dimensional population balances. Approximate moment methods are frequently used for their solution. In the present paper a new approach is presented, which is particular efficient when the number of internal coordinates is high. It combines the direct quadrature method of moments with monomial cubatures. With the new method the computational effort increases only polynomially, in the simplest case even only linearly with the number of internal coordinates, compared to an exponential increase for the well known Gausssian cubatures. The technique is evaluated for a five dimensional benchmark problem describing virus replication in continuous cell cultures. Furthermore, the algorithm is applied to analyze influenza virus replication in genetically modified cell lines.

      PubDate: 2016-12-06T13:10:17Z
       
  • Thermal bed mixing in rotary drums for different operational parameters
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): A.I. Nafsun, F. Herz, E. Specht, H. Komossa, S. Wirtz, V. Scherer, X. Liu
      The transversal thermal bed mixing was experimentally investigated in a batch rotary drum with a diameter of 0.6m and a length of 0.45m. The drum was filled with two fractions of granular material with different thermal conditions and the mixing temperature in the solid bed was measured with thermocouples located at different bed height. Quartz sand with a mean particle diameter of dP =0.2mm was used as test material. The operating parameters, rotational speed and filling degree of the drum were varied in the range of n=1–6rpm and F=10–20% respectively, whereas the influence on thermal mixing time was evaluated. The thermal mixing behavior was shown in terms of time constant, number of bed rotation, peak time and mixing number. Thermal mixing time decreases with higher rotational speed and lower filling degree. Comparison between experimental data and penetration model shows good agreement for low rotational speeds.

      PubDate: 2016-12-06T13:10:17Z
       
  • The effect of a drainage layer on the saturation of coalescing filters in
           the filtration process
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Cheng Chang, Zhongli Ji, Jialin Liu
      The effect of a drainage layer on the saturation of coalescing filters was evaluated experimentally. The effect of the pore size of a drainage layer on the saturation was demonstrated using the capillary theory. The experimental results showed that the filter without a drainage layer began to drain in the liquid film forming stage, where the flow resistance of the liquid in the channels increased significantly, resulting in the increases in both the saturation of the filter and the thickness of the liquid film. The pressure drop, saturation and liquid film thickness profiles varied after assembling a drainage layer outside of the coalescing layer. There was an adjustment stage of the liquid film in the filtration process of the filter with a non-wettable drainage layer, which can be verified by the evolution of the thickness of the liquid film predicted using theoretical calculations. The amount of the liquid increased gradually between the coalescing layer and the drainage layer at this stage, resulting in a significant increase in the saturation of the coalescing layer. As assembling a wettable drainage layer, a pseudo-steady state appeared, where the pressure drop and penetration were steady while the saturation of each layer increased. After the pressure drop increased and became steady again, the drainage led to a drastic increase in the saturation of the coalescing layer. At steady state of all the filters, the drainage rate and loading rate were almost the same. Furthermore, the capillary theory can be used to analyze the variation on the saturation affected by the pore sizes of a wettable drainage layer. Smaller pore size led to stronger capillarity, resulting in more liquid absorbed into the drainage layer and greater saturation of the coalescing layer.
      Graphical abstract image

      PubDate: 2016-12-06T13:10:17Z
       
  • Performance study of heat and mass transfer in an adsorption process by
           numerical simulation
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Dang Cheng, E.A.J.F. (Frank) Peters, J.A.M. (Hans) Kuipers
      In this work, a detailed three dimensional model is employed for the quantitative description of flow and coupled heat and mass transfer in a gas channel coated with porous adsorbent layer. The flow field of the gas stream is obtained by solving the Navier-Stokes equation. The highly coupled mass and heat transfer in both the gas channel and the adsorbent layer are locally described, and the accompanying adsorption/desorption dynamics in the adsorbent layer are modelled as well. A parametric study has been carried out, in which the influences of thermal conductivity of the adsorbent layer, specific heat, porosity, tortuosity, layer thickness and geometrical shape on the performance of moisture adsorption processes are investigated in an exhaustive way. The heat and mass transfer mechanisms in the investigated cases are thoroughly analysed taking advantage of the rigorous 3D model, which deepens our understanding on the intricately coupled transport processes. The results reported in this work are useful for rational design and optimization of adsorption processes in adsorbent coated gas channels.

      PubDate: 2016-12-06T13:10:17Z
       
  • A rigorous criterion for approach to cyclic steady-state in PSA
           simulations
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Surya Effendy, Shamsuzzaman Farooq, Douglas M. Ruthven
      An algorithm based on rigorous mathematical analysis is presented for determining the cyclic steady-state (CSS) in the simulation of Pressure Swing Adsorption (PSA) processes. The algorithm is founded on the observation that cyclic simulation of PSA processes is a Fixed-Point Iteration problem whose fixed point is the CSS. Therefore, instead of reducing the difference between the bed profiles of some dependent variables in two successive simulated cycles below a chosen tolerance value, the proposed algorithm reduces the difference between their current states and the CSS values to a set tolerance without requiring any a priori knowledge of the CSS. Three assumptions are made (1) convergence is linear in some neighbourhood of the CSS solution (2) the axial profiles at the end of the high pressure adsorption step moves only in one direction with respect to cycle number (3) the initial and ultimate convergence rates do not differ markedly. We demonstrate the effectiveness of the algorithm by applying it to a number of PSA/VSA/TSA processes simulated in the literature. For all the cases investigated, approach to the true CSS within a stated tolerance is achieved as indicated by the algorithm.

      PubDate: 2016-12-06T13:10:17Z
       
  • Stereo imaging camera model for 3D shape reconstruction of complex
           crystals and estimation of facet growth kinetics
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Rui Zhang, Cai Y. Ma, Jing J. Liu, Yang Zhang, Yu J. Liu, Xue Z. Wang
      The principle that the 3D shape of crystals that grow from a solution can be characterised in real-time using stereo imaging has been demonstrated previously. It uses the 2D images of a crystal that are obtained from two or more cameras arranged in defined angles as well as a mathematical reconstruction algorithm. Here attention is given to the development of a new and more robust 3D shape reconstruction method for complicated crystal structures. The proposed stereo imaging camera model for 3D crystal shape reconstruction firstly rotates a digitised crystal in the three-dimensional space and varies the size dimensions in all face directions. At each size and orientation, 2D projections of the crystal, according to the angles between the 2D cameras, are recorded. The contour information of the 2D images is processed to calculate Fourier descriptors and radius-based signature that are stored in a database. When the stereo imaging instrument mounted on a crystalliser captures 2D images, the images are segmented to obtain the contour information and processed to obtain Fourier descriptors and radius-based information. The calculated Fourier descriptors and radius-based signature are used to find the best matching in the database. The corresponding 3D crystal shape is thus found. Potash alum crystals that each has 26 habit faces were used as a case study. The result shows that the new approach for 3D shape reconstruction is more accurate and significantly robust than previous methods. In addition, the growth rates of {111}, {110} and {100} faces were correlated with relative supersaturation to derive models of facet growth kinetics.

      PubDate: 2016-11-30T04:56:46Z
       
  • The effects of reactor design on the synthesis of titanium carbide-derived
           carbon
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Michael R. Dutzer, Michael C. Mangarella, Jennifer A. Schott, Sheng Dai, Krista S. Walton
      Titanium carbide-derived carbon with residual metal is synthesized by partial chlorination at 500°C. This partial metal removal in the carbide creates vacancies, about which the carbon reorganizes to form an amorphous, porous carbon structure. To understand the titanium removal process on a bulk scale, three reactor designs were tested: (1) a flow-over horizontal-bed reactor, (2) a vertical flow-through packed-bed reactor, and (3) a fluidized-bed reactor. These reactors were chosen to investigate how various Cl2 flow patterns impact the etching uniformity on individual TiC-CDC particles. Both the horizontal- and packed-bed reactors lost approximately 10–15wt% of the original Ti content in 0.5h and lost more than 95wt% of the Ti content at 3h of etching; however, the fluidized-bed reactor lost approximately 85wt% of the original Ti content in 0.5h and reached a level of etching corresponding to more than 95wt% at 1h. Additionally, the horizontal- and packed-bed reactors were found to etch the TiC-CDC particles non-uniformly, while the fluidized-bed reactor produced samples with uniformly etched particles that followed the core-shell model of Ti extraction.

      PubDate: 2016-11-30T04:56:46Z
       
  • Characterizing the hydraulic properties of paper coating layer using
           FIB-SEM tomography and 3D pore-scale modeling
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): H. Aslannejad, S.M. Hassanizadeh, A. Raoof, D.A.M de Winter, N. Tomozeiu, M.Th. van Genuchten
      Paper used in the printing industry generally contains a relatively thin porous coating covering a thicker fibrous base layer. The three-dimensional pore structure of coatings has a major effect on fluid flow patterns inside the paper medium. Understanding and quantifying the flow properties of thin coating layers is hence crucial. Pore spaces within the coating have an average size of about 180nm. We used scanning electron microscopy combined with focused ion beam (FIB-SEM) to visualize the nano-scale pore structure of the paper coating layer. Post-processing of the FIB-SEM images allowed us to reconstruct the three-dimensional pore space of the coating. The 3D FIB-SEM images were analyzed in detail to obtain pore size distribution and porosity value. The permeability was estimated using the GeoDict software, based on solutions of the Stokes equation. By determining the porosity and permeability of increasingly larger domain sizes, we estimated the size of a representative elementary volume (REV) for the coating layer to be 60µm3, which is well within the volume analyzed using FIB-SEM. The estimated porosity and permeability of the REV domain were 0.34 and 0.09 mDarcy, respectively. Using the pore morphology method, capillary pressure-saturation (P c -S) and relative permeability curves of the REV domain could be constructed next. The P c -S curves showed that the coating had a high air entry suction, which is very favorable for printing in that ink will invade the coating as soon as it is applied to the coating. Our results are essential for macroscale modelling of ink penetration into a coating layer during inkjet printing. Macroscopic models can be valuable tools for optimization of the penetration depth and the spreading of ink on and within paper substrates.
      Graphical abstract image

      PubDate: 2016-11-30T04:56:46Z
       
  • The wound healing assay revisited: A transport phenomena approach
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Flora Ascione, Sergio Caserta, Stefano Guido
      The Wound Healing (WH) assay is one of the most popular methods for the analysis of cell migration in vitro, widely used to investigate physiological and pathological processes. Several experimental factors of difficult control, such as variation of cell density, hinder a reliable and reproducible application of this assay. We investigate the effect of cell density (from very low values to complete surface occupation) on WH assays on human fibrosarcoma cells, by using in vitro time-lapse microscopy. We found that wound closure velocity is linear with cell density, and explained this dependence by analyzing wound closure as a diffusion-reaction process, according to available models. This finding leads to a simple scaling of the experimental data to account for cell density differences, obtaining a significant improvement in the quantitative assessment of results. We also suggest a simple way to evaluate whether cell motility or proliferation drive the process, based on a non-dimensional parameter.

      PubDate: 2016-11-30T04:56:46Z
       
  • Computational Fluid-Dynamic modeling of the pseudo-homogeneous flow regime
           in large-scale bubble columns
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Besagni Giorgio, Fabio Inzoli, Thomas Ziegenhein, Dirk Lucas
      An understanding of the fluid dynamics and the transport phenomena in bubble columns (in the homogeneous and heterogeneous flow regimes) is of fundamental importance to support the design and scale-up methods. In this respect, multiphase Computational Fluid-Dynamics (CFD) simulations in the Eulerian multi-fluid framework are particularly useful to study the fluid dynamics in large-scale reactors; in particular, this study concerns the modeling of the fluid dynamics in bubble columns within the boundaries of the homogeneous flow regime. Reliable predictions of the homogeneous flow regime with this approach are, however, limited up to now. One important drawback is that usually the needed closure models for the interphase forces, turbulence and coalescence and break-up are selected case-by-case, which hinder improvement of the predictive value. A set of closure relations has been collected at the Helmholtz-Zentrum Dresden-Rossendorf that represents the best available knowledge and may serve as a baseline model for further investigations. In this paper, the validation of this set of closure relations has been extended to the pseudo-homogeneous flow regime—characterized by a wide spectrum of bubble sizes and typically associated with the large sparger openings used in industrial applications—in large-scale bubble columns, thus establishing a first step towards the simulation of industrial-scale reactors. To this end, the benchmark considered is a comprehensive dataset obtained for a large-scale bubble column, which has been built accordingly with the well-known scale up criteria (large-diameter, high aspect ratio and large sparger openings). The numerical approach has been tested in its fixed-poly-dispersed formulation (considering the two- and four-classes approaches to represent the dispersed phase) and considering the coalescence and break-up closures. The results suggest that the correct simulation of the fluid dynamics in the bubble column requires the definition of coalescence and break-up closures. The results have been critically analyzed and the reasons for the discrepancies between the numerical results and the experimental data have been identified and may serve as basis for future studies.

      PubDate: 2016-11-30T04:56:46Z
       
  • An experimental investigation into the behaviour of antifoaming agents
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Dale D. McClure, Marine Lamy, Lachlan Black, John M. Kavanagh, Geoffrey W. Barton
      As part of an on-going research program into the development of accurate computational fluid dynamics models of industrial bubble column bio-reactors, the behaviour of a range of commercially available antifoaming compounds was investigated. Experimental data from a laboratory scale system showed that increasing the antifoam concentration led to a decrease in the Oxygen Transfer Rate (OTR) up to a critical value, hypothesised to be related to the monolayer coverage of the gas-liquid interface; further increases in antifoam concentration had no additional impact. Beyond this critical antifoam concentration, a 3–5 fold reduction in the OTR was found, this reduction being independent of the type of antifoam used or the superficial air velocity. The issue of antifoam ‘deactivation’ was also examined with the results obtained being consistent with the deactivation of polyethylene oxide type antifoams being caused by their displacement from the gas-liquid interface by more hydrophobic material.

      PubDate: 2016-11-30T04:56:46Z
       
  • Investigating the partial structure of the hydrate film formed at the
           gas/water interface by Raman spectra
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Xin-Yang Zeng, Jin-Rong Zhong, Yi-Fei Sun, Sheng-Li Li, Guang-Jin Chen, Chang-Yu Sun
      The morphology and structure of hydrate films of pure methane and methane+ethane mixtures were studied by suspending a single gas bubble in liquid water. The methane+ethane gas mixtures, containing 20mol% or 81–89mol% methane, were used to form hydrate films with different crystal structures. Polyhedral structures appeared on the background of uniform polycrystalline hydrate films formed by gas mixtures with a high methane mole fraction of 0.81–0.82. Some of the polyhedral structures are holes, and others are separated structure II polyhedral hydrate crystals. However, for pure methane, a gas mixture with a lower CH4 mole fraction of 0.2, or a gas mixture with a higher CH4 mole fraction of 0.89, the morphology is uniform through the whole hydrate film. The crystal structures in the hydrate film were determined using in situ Raman spectra. The results show that both pure methane and the gas mixture with a lower CH4 mole fraction of 0.2 form a hydrate film with structure I. The single polyhedral crystal appeared in the background of the uniform polycrystalline hydrate film formed by gas mixtures with a high methane mole fraction of 0.81–0.82 as a structure II CH4-C2H6 double hydrate crystal. The hole is mainly gas with an initial small amount of structure I hydrate, and that hole will be filled with structure II hydrate after a certain time. The experimental methods and the new findings presented in this work should be significant for the further research of hydrate growth kinetics.

      PubDate: 2016-11-30T04:56:46Z
       
  • Thin poly(ether-block-amide)/attapulgite composite membranes with improved
           CO2 permeance and selectivity for CO2/N2 and CO2/CH4
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Long Xiang, Yichang Pan, Jinlong Jiang, Ye Chen, Jing Chen, Lixiong Zhang, Chongqing Wang
      Composite membrane with a thin selective layer on porous polymer substrate is more attractive than the asymmetric polymer membrane. In this study, a thin layer of attapulgite-poly(ether-block-amide) (ATP-Pebax) hybrid material was successfully deposited on a porous polyacrylonitrile (PAN) support to form a composite membrane. The poly[1-(trimethylsilyl)-1-propyne] (PTMSP) gutter layer plays the crucial role in decreasing the thickness of ATP-Pebax selective layer due to its superior hydrophobicity. A contact 2wt% ATP-Pebax selective layer (~700nm) was successfully deposited on the PAN support. The CO2 permeance on the composite membrane was significantly improved from 2.6 to 108 GPU, compared with the 2wt% ATP-Pebax freestanding membrane. The ideal selectivity for CO2/N2 and CO2/CH4 were also enhanced by 35% and 16%, respectively. The gas permeability in ATP fillers were achieved by adsorptive measurements and validated by the generalized Maxwell model for ATP-Pebax hybrid materials. The effect of the feeding pressure and permeating temperature on both single and mixed gas permeation were examined. The separation performance on the composite membranes under dry and humidified-state feeding were also compared. The optimized separating performance of the thin ATP-Pebax composite membrane are attractive for potential applications like natural gas sweetening or biogas purification.

      PubDate: 2016-11-30T04:56:46Z
       
  • Coupled autocatalytic reactions: Interconversion and extinction of species
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Aditi Khot, S. Pushpavanam
      An autocatalytic reaction involves a species catalyzing its own formation and can be viewed as a mechanism to explain self-replication. This class of chemical reactions can be used to model phenomena across a wide cross-section of disciplines, i.e chemical reaction engineering, biology, ecology, social sciences and economics. Here, we study a system of two species undergoing autocatalysis. Each species participates in the autocatalysis of the other. The autocatalytic reactions can represent interconversion of two social groups or isomers into each other. The two autocatalytic steps are assumed to be elementary and follow cubic and quadratic laws. We examine the behavior of this coupled autocatalytic system at steady state. Specifically, singularity theory and bifurcation theory are applied to classify the bifurcation behavior of the system. The focus of the work is to obtain the conditions for extinction or complete conversion of one of the species. We analyze the system for all combinations of generation and decay reactions. We find the common features and dominant factors in the different combinations analyzed.
      Graphical abstract image

      PubDate: 2016-11-30T04:56:46Z
       
  • Molten salt chemical looping for reactive separation of HBr in a
           halogen-based natural gas conversion process
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): D. Chester Upham, Zachary R. Snodgrass, Mojgan Tabatabaei Zavareh, Thomas B. McConnaughy, Michael J. Gordon, Horia Metiu, Eric W. McFarland
      Hydrogen bromide (HBr) oxidation to molecular bromine (Br2) is demonstrated in a chemical looping process using a molten bromide salt. The two-step process is operated at 500°C and first contacts oxygen with molten KBr-LiBr-NiBr2 to form Br2 gas and a suspension of nickel oxide (NiO) particles in one reactor. The oxide suspension is then contacted with HBr to regenerate the bromide salt and produce steam. Sixty-eight metal oxides/bromides were considered. The cyclic interconversion between oxide and bromide, by alternating exposure to HBr and oxygen, at a single temperature was only possible with nickel. In contrast to solid-based chemical looping systems, the liquid bromide salt (NiBr2 dissolved in KBr-LiBr eutectic) was found to be cycleable without attrition or deactivation. Further, when mixtures of olefins and hydrogen bromide were reacted with the oxide suspension, selective oxidation of HBr was observed without hydrocarbon oxidation. High selectivity for HBr oxidation is due to the solubility of HBr in the molten salt, which allows contact with NiO, whereas, the insoluble hydrocarbons do not contact the reactive oxide. A process model that makes use of reactive separation of HBr from hydrocarbons and process intensification using molten salt-based chemical looping is presented as a potentially lower cost alternative to a process model using conventional separations in bromine-based methane conversion. The total heat exchanged in a corrosive environment in the molten salt based process is 205MW, and the heat exchanged in a corrosive environment in the conventional process is 581MW.
      Graphical abstract image

      PubDate: 2016-11-30T04:56:46Z
       
  • Single phase mixing in coiled tubes and coiled flow inverters in different
           flow regimes
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Loveleen Sharma, K.D.P. Nigam, Shantanu Roy
      The present study focuses on the measurement of residence time distribution (RTD) in coiled tubes and coiled flow inverters (CFI) over a wide range of Reynolds numbers (N Re ), in contrast to earlier studies that have reported the RTD over a very narrow range, mainly restricted to the laminar region. The analysis of our experimental data reveals the existence of three distinct flow regimes in coiled structures, viz. laminar flow with prominent Dean circulation, laminar flow with less contribution of Dean circulation, and fully developed turbulent flow. Even though the turbulent transition is known to be delayed in coiled geometries, good radial mixing brought in by Dean circulation results in a narrow RTD of the exiting fluid even when the flow is clearly laminar. For coiled flow inverters, the 90° inversion allows further enhanacement in overall mixing, albeit at the cost of extra pressure drop. The effect of different design parameters on the role of secondary flow for coiled geometries of varying number of inversions (n) and curvature ratios ( λ ) has been investigated. Finally, a master plot is developed between the dispersion number ( D / U d t ) and Reynolds number (N Re ) showing the marked improvements in cross-sectional mixing in coiled flow, over that in straight tubes. Based on this, a correlation is presented.

      PubDate: 2016-11-30T04:56:46Z
       
  • Application of film theory on the reactions of solid particles with
           liquids: Shrinking particles with changing liquid films
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Tapio Salmi, Vincenzo Russo, Claudio Carletti, Teuvo Kilpiö, Riccardo Tesser, Dmitry Murzin, Tapio Westerlund, Henrik Grénman
      The reactivity of soluble solid particles with liquids was described with extended film theory: the solid material dissolves in the liquid phase and diffuses through the liquid film surrounding the particle. In both the liquid film and bulk liquid, chemical reactions take place. The solid particle shrinks due to the dissolution and consequent reactions and the film becomes thinner and thinner due to the decreasing particle size. A general mathematical model was developed for the solid particle, the liquid film and the liquid bulk phase. The dynamic models were based on mass balances for the solid, film and bulk liquid. The models consisting of coupled parabolic partial differential equations and ordinary differential equations were solved numerically by applying the method of lines. The gPROMS ModelBuilder was used in the computations of generic cases. The models predict the shift of the reaction domain being predominantly located in the liquid film towards the liquid bulk during the progress of the solid-liquid process. The roles of the liquid film and the liquid bulk phases were illustrated with contribution analysis.
      Graphical abstract image

      PubDate: 2016-11-30T04:56:46Z
       
  • Stability and convergence of computational eulerian two-fluid model for a
           bubble plume
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Avinash Vaidheeswaran, Martin Lopez de Bertodano
      The Eulerian two-fluid model (TFM) of Ishii (1975) is used to analyze the dynamics of an air-water bubble plume. The focus is on the effect of the linear stability, in particular the ill-posed condition, on the nonlinear stability of the TFM. It is well-known that the TFM for bubbly flows is ill-posed as an initial value problem in the absence of short wavelength physics for non-zero slip velocities. It is also known that the 1-D TFM can be made conditionally well-posed (for void fraction <26%) by adding momentum transfer due to interfacial pressure difference and virtual mass. However, there is still the possibility of a TFM being ill-posed in regions of higher void fractions (void fraction >26%). Physically, as the void fraction increases, the bubbles tend to undergo collisions, and the momentum transfer due to this mechanism may become significant. In the current study a bubble collision model adapted from the work of Alajbegovic et al. (1999) is used for CFD TFM calculations for bubbly flows using an LES approach. It is shown by linear stability analysis and non-linear simulations that the collision term makes the TFM unconditionally well-posed and stable in a non-linear sense. Secondly, computational grid convergence tests are performed with the well-posed CFD TFM. It is observed that the coarse grid solution exhibits an unphysical limit cycle behavior that is inconsistent with turbulence, but as the mesh is refined the solution becomes chaotic. CFD TFM simulations commonly employ a grid restriction to avoid ill-posed behavior. However, this is unnecessary with a well-posed Eulerian TFM derived from first principles using the continuum assumption. Once the restriction is removed by adding appropriate short-wavelength physics, i.e., interfacial pressure difference and collision mechanism, convergence may be approached in a statistical sense consistent with a turbulent CFD model.

      PubDate: 2016-11-30T04:56:46Z
       
  • Experimental and numerical investigation of single-phase hydrodynamics in
           glass sponges by means of combined µPIV measurements and CFD simulation
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Sebastian Meinicke, Christian-Ole Möller, Benjamin Dietrich, Michael Schlüter, Thomas Wetzel
      The following paper presents a combined experimental and numerical approach to analyze single-phase hydrodynamics inside porous SiO2 glass sponges (=open-cell foams). For this purpose, a µPIV method has been applied to visualize instantaneous velocity fields of refractive index-matched aqueous Dimethyl sulfoxide (=DMSO) solution flow through the voids of the complex, irregular structure. Results have been recorded for a superficial flow velocity range from 0.02 to 0.38m/s (corresponding to Reynolds number values between 30 and 650), covering – according to available classifications in literature – all distinguished flow regimes inside such porous systems. µPIV data is used to substantiate the existence of different flow regimes in irregular porous media, to detect their particular flow characteristics and to track the transition points between the prevailing flow regimes. Furthermore, µPIV data has been time-averaged and compared to corresponding numerical results of a laminar, steady-state CFD modelling approach, which is based on reconstructions of the real sponge geometry gained from X-ray tomographic scans of the structure. Experimental and numerical results of pore-scale velocity fields have been compared at three different measurement positions and show good agreement in terms of observed flow structure and direction as well as magnitude of the respective mean velocity fields.

      PubDate: 2016-11-23T10:20:29Z
       
  • LaMO3 perovskites (M=Co, Cu, Fe and Ni) as heterogeneous catalysts for
           activating peroxymonosulfate in water
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Kun-Yi Andrew Lin, Yu-Chien Chen, Yi-Feng Lin
      Although perovskites are extensively investigated in many areas, studies using perovskites as catalysts to activate oxidants for chemical oxidations are still quite limited. While various transition metals can be inserted into perovskites to form different perovskites, it is critical to investigate the effects of various transition metallic substituents on the activation of oxidants in chemical oxidation reactions. In this study, we propose to evaluate various metallic substituents in Lanthanum (La)-based perovskites (LaMO3 (M: Co, Cu, Fe and Ni)) for activating a strong oxidant, peroxymonosulfate (POMS), in order to degrade organic contaminants. Rhodamine B (RB) decolorization is used as a model test to evaluate generation of sulfate radicals from activation of POMS by LaMO3. LaCoO3 was found to exhibit the highest catalytic activity, followed by LaNiO3, LaCuO3 and then LaFeO3. LaCoO3 was then selected as a representative LaMO3 to be further investigated for the behavior of POMS activation under various conditions. LaCoO3-activated POMS was favorable under neutral conditions and at high temperatures, but less effective in the presence of NaCl. The mechanism of RB decolorization by LaCoO3-activated POMS was elucidated by examining the effects of radical inhibitors and attributed primarily to sulfate radicals and hydroxyl radicals to a lesser extent. We also found that both La3+ and Co3+/Co2+ ions contribute to catalytic decomposition of POMS for yielding sulfate radicals. LaCoO3 was also shown to activate POMS for RB decolorization over multiple trials without losing efficiency. These results reveal that LaCoO3 is a recyclable and effective La-based perovskite for POMS activation, which can be used for degradation of organic contaminants.

      PubDate: 2016-11-23T10:20:29Z
       
  • Dynamic allocation of industrial utilities as an optimal stochastic
           tracking problem
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Pablo S. Rivadeneira, John A.Gómez Múnera, Vicente Costanza
      A new dynamic optimization strategy is substantiated for allocating demands, in a typical process plant, to a set of service equipment working in parallel. It is a stochastic process in nature, but its optimal control is based on the solution to a related deterministic optimal tracking problem to minimize a quadratic cost objective restricted by linear dynamics. The main theoretical novelty, demonstrated here, is the separation theorem for the stochastic tracking problem. This means: the desired optimal stochastic solution can be calculated from the solution to the deterministic problem, by replacing the state variable with their optimal estimates, which can be generated online following a Kalman filter scheme. The set-points assigned to each conventional controlled device are allowed to be continuously changed while: (i) minimizing a combined cost, which is cumulative in time and takes into account the dynamics of all the individual utilities, and (ii) generating a feedback law that can cope with general disturbances, like changes in fuel composition and with noisy measurements, i.e. with differences between the predicted and the measured values of the variables.

      PubDate: 2016-11-23T10:20:29Z
       
  • Assessment of polydisperse drag models for the size segregation in a
           bubbling fluidized bed using discrete particle method
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Yong Zhang, Yuemin Zhao, Liqiang Lu, Wei Ge, Junwu Wang, Chenlong Duan
      Polydisperse gas-particle flow is often encountered in industry and many polydisperse drag models have been developed in literature. In this work, discrete particle method was employed to assess polydisperse drag models for the segregation and mixing of binary gas-particle flow in a bubbling fluidized bed. The degree of particle segregation and the characteristic bubble frequency using different polydisperse drag models were analyzed. It was shown that the results predicted by the model of Rong et al. (2014) are in a best agreement with experimental data with 5.3% errors on average, and two dominant bubble frequencies were found by analyzing the fluctuations of average particle height.
      Graphical abstract image

      PubDate: 2016-11-23T10:20:29Z
       
  • An experimental study on the reproducibility of different multilayer OLED
           materials processed by slot die coating
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): S.M. Raupp, L. Merklein, M. Pathak, P. Scharfer, W. Schabel
      In this work we aim at solution-processed multilayer organic light emitting diodes (OLEDs) with slot die coating as a scalable technology. We apply small molecules, polymers and polymer-host systems as emissive layers. The emissive layers are slot die coated on slot die coated Pedot:PSS. All experiments are performed with commercially available materials, aiming to establish a fundamental knowledge about processing these different materials from solution. The coating was carried out on indium tin oxide glass substrates with a table coater under ambient conditions. The focus is on the reproducibility and the processing itself. Several batches of OLEDs were produced for reproducibility and averaged values of 200 OLEDs in total were measured to ensure the reliability of the data. We demonstrate devices with two slot die coated organic layers reaching ~ 5cd/A at low standard deviation.
      Graphical abstract image

      PubDate: 2016-11-23T10:20:29Z
       
  • Numerical assessment of the effects of carbon deposition and oxidation on
           chemical looping combustion in a packed-bed reactor
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Diglio Giuseppe, Bareschino Piero, Mancusi Erasmo, Pepe Francesco
      Chemical looping combustion with methane as fuel in a packed-bed reactor using Ni as oxygen carrier was numerically investigated. To this aim, a mathematical model that takes into account both oxidation and reduction phases was developed. To describe catalyst fouling due to carbon deposition, CH4 decomposition and carbon regasification by steam and CO2 (Boudouard reaction) were considered during reduction phase, while carbon combustion was taken into account during oxidation phase. A catalyst deactivation function due to carbon accumulation on oxygen carrier was introduced too. In the paper the effects of fouling on the operability of packed-bed reactor was studied, focusing the attention on the switch strategy adopted. Results show that a detailed description of carbon deposition and consumption phenomena is an essential prerequisite to properly operate a CLC process. Indeed, it was found that working with variable oxidation and reduction time lengths, the power produced is about three times greater than of that obtainable operating with fixed times. Although carbon deposition can be also reduced by increasing the H2O:CH4 feed ratio, it was found that in this case the power produced decreases by about 30% with respect to that obtained operating with variable oxidation and reduction time lengths.
      Graphical abstract image Highlights fx1

      PubDate: 2016-11-17T12:56:38Z
       
  • Ultra-stable aqueous foams with multilayer films stabilized by
           1-dodecanol, sodium dodecyl sulfonate and polyvinyl alcohol
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Xing Du, Lei Zhao, Xuan He, Hui Chen, Wei Fang, Weixin Li
      Ultra-stable foams with multilayer films which were similar to the structure of colloidal gas aphrons (CGA) were designed in view of increasing the amount of bound water molecules at molecular level. This liquid films in foams were spontaneously assembled by 1-dodecanol (DDA), sodium dodecyl sulfonate (SDS) and polyvinyl alcohol (PVA) molecular with a remarkable long-term foam lifetime. The states of water molecules as well as the molecular arrangement in foam films have been analyzed via molecular dynamics (MD) simulation to explore microscopic character and stable mechanism of multilayer films of foams. We found that the combined effect of SDS, DDA and PVA could not only increase distribution intensity of bound water molecules in foam film layers, but it also could decrease the gas diffusion rate to balance the pressure of the air layers of the multilayer foams.

      PubDate: 2016-11-17T12:56:38Z
       
  • Statistical evaluation and discrimination of competing kinetic models and
           hypothesis for the mathematical description of poly-3(hydroxybutyrate)
           synthesis by Cupriavidus necator DSM 545
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Daniela E.G. Trigueros, Camila L. Hinterholz, Mônica L. Fiorese, Gláucia M.F. Aragão, Willibaldo Schmidell, Maria A.M. Reis, Alexander D. Kroumov
      A robust statistical approach for discrimination of competing microbial growth kinetics models was applied. The phenomenological modeling approach based on unstructured and non-segregated kinetic models was formulated to describe PHB synthesis by Cupriavidus necator that experimentally was carried out in batch system for the given temperatures of 30; 32.5; 35 and 37.5°C. Further, PHB synthesis was assumed to be non-growth-associated under nitrogen limitation conditions. The stoichiometry of the microbial growth and PHB synthesis was successfully used in kinetics studies combining the knowledge with the deterministic models in ordinary differential equation system. The parameters of the models identification procedure was based on the Genetic Algorithms which were coded in Maple®15 software. Analysis of the normalized least square function, as well as the correlation coefficient, has shown that all competing kinetic models fitted well the experimental data in all studied temperatures. A sequence of statistical tests was used to evaluate the quality of the chosen competing kinetic models and their ability to fit to the experimental data, and more particularly to ensure the reliability of the best model predictions. Hence, as a result was ensured that the mathematical modeling based on Andrews (1968) model was the one that best described the experimental data under the given operational conditions and more particularly obtained at 32.5°C. The evaluated values of parameters indicated that the specific growth rate (SGR) of active biomass most likely was limited since the nutrient nitrogen concentration was SN ≤3.35gL−1, and the specific production rate (SPR) of PHB was maximum when the organic substrate concentration reached SC =10gL−1. Moreover, the experimental tests have shown that the highest biomass (0.361gcellL−1 h−1) and PHB (0.50gPHBL−1 h−1) productivity were attained at 32.5°C. Andrews (1968) model provide interesting findings for the given oxygen mass-transfer conditions from the gas to the liquid phase and the microbial respiration during the cultivation at 32.5°C. The cell respiration parameters estimated by GA were 0.89gcell gO 2 − 1 in the growth phase and 0.31gcell gO 2 − 1 in the PHB synthesis phase. These values agreed with those ones found from the stoichiometry of microbial growth and PHB synthesis demonstrated in this study. Thus, application of statistical test analysis can be considered as a powerful tool for discrimination of kinetic hypothesis about the dynamics of the cell growth and product synthesis.

      PubDate: 2016-11-17T12:56:38Z
       
  • An overview of sulfidogenic biological reactors for the simultaneous
           treatment of sulfate and heavy metal rich wastewater
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): M. Gopi Kiran, Kannan Pakshirajan, Gopal Das
      Microbial precipitation of heavy metals by sulfate reducing bacteria (SRB) through sulfate reduction as corresponding sulfides is being seen as a promising technique for the treatment of metal contaminated wastewater. SRB based bioprocesses are more attractive compared with chemical process owing to their low cost, very high removal and recovery of metals even at low initial concentration from wastewater. Both passive and active biological treatment systems are regarded as the most promising and potential treatment systems for a wide variety of metallic wastewater. These bioreactor systems offer more compact design, ease of performance and efficient control. However, there is limited information available on sulfidogenic bioreactors in the literature for a better understanding of the treatment system involving SRB. This is particularly important for scaling up of the potential of these systems. Hence, in this article, the highlights of different reactors (passive and active) used for treating sulfate and metal containing wastewater, factors affecting the process parameters, effect of different electron donors, merits and demerits of various reactors are emphasized.

      PubDate: 2016-11-17T12:56:38Z
       
  • EDTA-Cu (II) chelating magnetic nanoparticles as a support for laccase
           immobilization
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Raquel A. Fernandes, Ana Luísa Daniel-da-Silva, Ana P.M. Tavares, Ana M.R.B. Xavier
      Developments in nanotechnology have led to the discovery of new materials, namely, magnetic nanoparticles (MNPs), that present easy surface functionalization and high surface-to-volume ratios. These properties allow a high mass transfer rate and easy removal from a reaction matrix. Simple separation under an external magnetic field makes them a promising immobilization support for enzymes. In this work, new MNPs were prepared by functionalization with EDTA-TMS and characterized by TEM, FTIR and BET analytical techniques, among others. These MNPs were applied as support for laccase immobilization to create a promising biocatalyst. Despite the known chelating nature of EDTA-TMS, its use for surface modification of MNPs for laccase immobilization is a rather unexplored strategy and is reported here for the first time. At pH 3.5, the immobilization process showed approximately 97% of enzymatic activity recovery. The Michaelis-Menten kinetic properties of immobilized laccase showed a lower Vmax and a similar KM compared to free laccase. Regarding operational stability, the immobilized enzyme presented approximately 73% of its initial activity after five sequential reactive cycles. The immobilized enzyme was successfully applied to the biocatalysis of Indigo Carmine dye degradation. These MNPs with immobilized laccase showed important advantages compared to other materials for application in industrial biochemical processes, biocatalysis and biosensors.
      Graphical abstract image

      PubDate: 2016-11-17T12:56:38Z
       
  • Using chaos analysis for evaluating the quality of F-PIV measurements in a
           bubble column
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Helder Lima de Moura, Rodrigo de Lima Amaral, Diana Isabe Sánchezl Forero, Guilherme J. de Castilho, Sávio Souza Venâncio Vianna, Milton Mori
      A new approach is proposed for evaluating the quality of fluorescent particle image velocimetry (F-PIV) measurements for different superficial gas velocities (UG) in a bubble column (1.0m long×0.145m i.d.) using chaos analysis. The 2D velocity fields of a F-PIV system were obtained in a 0.145×0.10m area located 0.552m above the gas distributor. Four thousand pairs of images were obtained at a frequency of 4.2Hz at nine radial positions for superficial gas velocities (UG) of 0.158, 0.528, 2.106 and 4.212×10−2 m/s. Using the standard cross-correlation (SCC) approach, PIV quality was analyzed for the velocity module and its components by investigating the cross-correlation coefficient (CCC), the signal-to-noise ratio (SNR) and the uncertainty (CS method) estimated by correlation statistics. Moreover, it was possible to extract the velocity fluctuation series for chaos analysis (correlation dimension, DML, and standard deviation of the correlation integral, DevML). The effect of the quality of F-PIV measurements evaluated by chaos analysis is based on the noise limitation in amplitude and normalization of the integral correlation distances. The results presented similarities in the behavior of the PIV uncertainty and chaotic parameters along the radius for all UG investigated. For this reason, chaos analysis can be used in other PIV processing settings where quality indicators, such as uncertainty, SNR and CCC, do not exist. Thus, it was possible to use this analysis to gain a better understanding of the nonlinear interactions in a bubble column as well as the performance of a PIV post-processing filter in order to reduce the effect of noise.
      Graphical abstract image

      PubDate: 2016-11-17T12:56:38Z
       
  • A DNS study of flow and heat transfer through slender fixed-bed reactors
           randomly packed with spherical particles
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Saurish Das, Niels G. Deen, J.A.M. Kuipers
      A fully resolved direct numerical simulation of flow and heat transfer is presented for slender randomly packed bed reactors. The flow and temperature field are solved over a non-body fitted, non-conformal Cartesian computational domain. The coupling between fluid and solid (both spherical particles and cylindrical wall) is enforced by a second order accurate, sharp interface immersed boundary method (IBM). The present numerical technique neither requires any challenging volumetric mesh generation process nor demands manipulation of the geometry near the particle-particle and particle-wall contact points. Conjugate heat transfer has been considered where the temperature field is calculated both inside the solid particles and in the fluid. A discrete element method (DEM) is used to generate the random packings of spherical particles in the cylindrical column, and a methodology is proposed to calculate the radial porosity profile of the bed. The column-to-particle diameter ratio (N) is varied from 4 to 8, and two separate cases have been considered where N → ∞ . The particle Reynolds number (Re d ) is varied from 1 to 500. The numerically obtained pressure drop and overall wall-to-bed heat transfer coefficient for different simulation cases are critically compared with empirical correlations and a good agreement is reported. Moreover, based on the current numerical results, correlations are proposed for the pressure drop and the wall-to-bed heat transfer coefficient. The effect of the column-to-particle diameter ratio (N) on both the flow and heat transfer, as-well-as the effect of the solid to fluid thermal conductivity ratio on the conjugate heat transfer are discussed. Furthermore, the fully resolved accurate numerical simulations have helped to elucidate the detailed pore-scale flow and heat transfer feature in the packed beds.
      Graphical abstract image Highlights fx1

      PubDate: 2016-11-17T12:56:38Z
       
  • Modeling study of gas-liquid mass transfer enhancement by cylindrical
           catalyst particles
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): Dang Cheng, Steven Wang, J.A.M.(Hans) Kuipers
      In this work, the influences of non-spherical catalyst particles on the enhancement of the gas-liquid mass transfer are numerically studied. The 3D unsteady diffusion-reaction equation both in the liquid phase and the solid catalyst particles is solved. A pseudo-homogenous model is employed as well. It is found that the SV cylindrical particles increase enhancement factor while SRSV cylindrical particles decrease it in comparison with the corresponding spherical particles. The horizontal cylinder and the vertical cylinder show small differences. The enhancement factor increases with catalyst concentration, rate coefficient of reaction and decreasing particle size. The data of pseudo-homogenous model agree well with the corresponding results of the fully resolved simulations.

      PubDate: 2016-11-17T12:56:38Z
       
  • Oxygen storage dominated three-way catalyst modeling for fresh catalysts
    • Abstract: Publication date: 16 March 2017
      Source:Chemical Engineering Science, Volume 160
      Author(s): J. Bickel, B. Odendall, G. Eigenberger, U. Nieken
      Meeting future legislations for the emissions of spark-ignition engines requires the development of efficient three-way catalyst (TWC) models. These models can both be employed for online catalyst control as well as model-based development of control and on-board diagnosis (OBD) strategies. In this paper we present such a model that aims at capturing transient TWC dynamics of fresh catalysts at elevated temperatures. Applying a parameter subset selection strategy, we demonstrate that solely taking into account the dynamics of oxygen storage and release is sufficient for this purpose and reactions associated with processes taking place on the platinum-group metals do not have to be modeled explicitly. The one-dimensional single channel model lumps the exhaust gas species into two pseudo components, one being able to oxidize and one being able to reduce the oxygen storage material. The respective reaction kinetics are considered reversible with non-linear functions depending on the oxidation state of the material being put in the center of focus. Model validation is carried out using experimental data from an isothermal synthetic gas test bench. The applied feed gas composition closely resembles real exhaust conditions under dynamic operation. By employing local parameter sensitivity and identifiability analysis and investigating the differences between a total of five fresh catalysts from different commercial suppliers, we propose a set of only five parameters that can be used to accurately model oxygen storage and release dynamics under isothermal conditions. The results emphasize the importance of accounting for oxygen storage from water as well as the need of using a spatially distributed model. Apart from the above mentioned applications, the model is shown to be suitable for fast catalyst screening and characterization.

      PubDate: 2016-11-17T12:56:38Z
       
  • Highly efficient mechanochemical synthesis of an indium based
           metal-organic framework with excellent water stability
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Yongwei Chen, Jing Xiao, Daofei Lv, Tiezhen Huang, Feng Xu, Xuejiao Sun, Hongxia Xi, Qibin Xia, Zhong Li
      Mechanochemical synthesis, induced by mechanical grinding, is demonstrated to be rapid and efficient for metal-organic frameworks (MOFs) synthesis. For this purpose, a mechanochemical synthesis route was proposed for the first time for preparation of water stable indium metal-organic frameworks InOF-1. The effects of preparation conditions such as the addition of solvents and grinding time were discussed, and the InOF-1 synthesized through optimized condition was used to investigate its selective CO2 adsorption. Results showed that using liquid-assisted grinding for 20min with CH3CN (0.4mL) could lead to highly crystalline and porous InOF-1 with a Brunauer-Emmett-Teller (BET) surface area of 707m2/g. The addition of a small amount of solvent into the system could dramatically improve the crystallinity and porosity of InOF-1. More importantly, the synthesized product with the highest specific surface area retained its crystallinity and porosity after being soaked in water for 12h. Its CO2 adsorption capacity reached as high as 4.03mmol/g at 273K and 100kPa, and CO2/CH4 and CO2/N2 adsorption selectivities were up to 7.5 and 45, respectively. The superior performance of the mechanochemically synthesized InOF-1 makes it a potential candidate for CO2 adsorption and separation.
      Graphical abstract image

      PubDate: 2016-11-11T13:26:17Z
       
  • Modelling of artefacts in estimations of particle size of needle-like
           particles from laser diffraction measurements
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Okpeafoh S. Agimelen, Anthony J. Mulholland, Jan Sefcik
      Manufacturing of particulate products across many industries relies on accurate measurements of particle size distributions in dispersions or powders. Laser diffraction (or small angle light scattering) is commonly used, usually off-line, for particle size measurements. The estimation of particle sizes by this method requires the solution of an inverse problem using a suitable scattering model that takes into account size, shape and optical properties of the particles. However, laser diffraction instruments are usually accompanied by software that employs a default scattering model for spherical particles, which is then used to solve the inverse problem even though a significant number of particulate products occur in strongly non-spherical shapes such as needles. In this work, we demonstrate that using the spherical model for the estimation of sizes of needle-like particles can lead to the appearance of artefacts in the form of multimodal populations of particles with size modes much smaller than those actually present in the sample. This effect can result in a significant under-estimation of the mean particle size and in false modes in estimated particles size distributions.

      PubDate: 2016-11-05T14:22:24Z
       
  • A new method for ultra-fast concentration of hydrophobic particles
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): K.P. Galvin, K. van Netten
      In froth flotation, fine hydrophobic particles selectively attach to the surface of air bubbles, in turn rising through the liquid and then more slowly as part of the foam that emerges from the system. This paper proposes a paradigm shift from the traditional use of air bubbles as the hydrophobic separation medium to potentially a far more powerful version that utilises a novel hydrophobic binder, a concentrated water in oil emulsion. We show empirically the oil consumption increases linearly with the specific surface area of the particles, with an average oil film thickness of 178nm for fine coal particles, well below the level required for conventional oil agglomeration. The new approach is ultrafast, achieving agglomeration within seconds under batch conditions, with strong selectivity. We also show for the first time continuous steady state agglomeration can be achieved by simply passing the feed and binder suspensions through a partially closed ball valve. Here the residence time through the valve is less than 0.1s. And, by subjecting the agglomerated product to further shear, the emulsion is inverted, releasing bound water. Pressure driven filtration then delivers remarkably low product moistures. Operational aspects of this new technology are discussed.

      PubDate: 2016-11-05T14:22:24Z
       
  • Predicting breakage of high aspect ratio particles in an agitated bed
           using the Discrete Element Method
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Y. Guo, C. Wassgren, B. Hancock, W. Ketterhagen, J. Curtis
      Predicting particle breakage is critical for the control of particle size in some bulk solids handling processes, such as those found in the pharmaceutical, food, consumer product, and mineral processing industries. This article presents a computational study of the breakage of high aspect ratio particles subject to mechanical agitation using the Discrete Element Method (DEM), in which a particle, represented by a string of bonded spheres, breaks at the center of a bond where the tensile or shear stress exceeds the material strength. The numerical model is validated using experimental results from the breakage of blackboard chalk sticks subject to uniaxial compression in a cylindrical container. The validated model is used to investigate particle breakage when agitated by rotating blades, which is encountered in a range of pharmaceutical processes, such as agitated filter drying, rotary tablet press feeding, and powder blending. The simulation results show that the breakage rate, that is the rate of particle size reduction (or the rate of fragment mass increase), increases as the applied pressure, impeller rotational speed, particle-particle friction, or particle-equipment friction increases. However, the extent of breakage per impeller revolution is independent of impeller rotational speed. Most importantly, it is found that the extent of particle breakage is a function of the work performed on the material, and the parameters in this function depend on the particle-particle and particle-wall friction coefficients. Large friction coefficients enable the input energy to break the particles more efficiently.
      Graphical abstract image

      PubDate: 2016-10-30T12:06:27Z
       
  • Fabrication of gold nanoparticles in confined spaces using solid-phase
           reduction: Significant enhancement of dispersion degree and catalytic
           activity
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Zhi-Min Xing, Yu-Xia Gao, Li-Ying Shi, Xiao-Qin Liu, Yao Jiang, Lin-Bing Sun
      Au-containing catalysts are highly active in diverse reactions, and their activity strongly depends on the dispersion degree of Au. Here we report for the first time a solid-phase reduction strategy to promote Au dispersion in template-occluded SBA-15 (AS) by fully considering three crucial factors, namely (i) the interaction between Au and supports, (ii) the space where Au precursors locate during reduction, and (iii) the reduction method. First, both template and silica walls in AS offer interaction with Au species. Second, AS presents confined spaces between template and silica walls. Third, the reduction in solid phase avoids the competitive adsorption of solvent molecules. The results show Au-containing AS has a better dispersion of Au than its counterpart prepared from template-free SBA-15 (CS). Moreover, the obtained materials exhibit excellent catalytic activity in reduction reactions and that the organic template retained in mesopores promotes the reactions greatly.
      Graphical abstract image

      PubDate: 2016-10-30T12:06:27Z
       
  • HLADH-catalyzed synthesis of β-amino acids, assisted by continuous
           electrochemical regeneration of NAD+ in a filter press microreactor
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Rossmery A. Rodríguez-Hinestroza, Carmen López, Josep López-Santín, Cheikhou Kane, M. Dolors Benaiges, Theo Tzedakis
      This work focuses on the use of electrochemical microreactors, applied to the direct electroregeneration of nicotinamide dinucleotide (NAD+) used in-situ for the enzymatically-assisted oxidation of the β-alanine. Mechanistic and chemical/electrochemical reactor approaches were investigated, to achieve satisfactory conversions (>80%) of the substrate in reasonable (1–2 days) reaction times; no fouling observed of the gold anode. An original method was proposed to limit the complexation effect of the produced β-alanine to the enzyme. Simulations of the overall system were achieved and an estimation of the required kinetic and Michaelis constants was proposed.

      PubDate: 2016-10-30T12:06:27Z
       
  • Spatial quantification of hydrogels swelling using wide-field fluorescence
           microscopy
    • Abstract: Publication date: 2 February 2017
      Source:Chemical Engineering Science, Volume 158
      Author(s): Weiji Liu, Xiao Dong Chen, Ruben Mercadé-Prieto
      Wide-field fluorescence microscopy (WFM) is used to spatially quantify the protein content of large hydrogels during swelling. Whey protein gels made at different protein concentrations, labelled with rhodamine B isothiocyanate (RITC), were used as a model system. Labelling and swelling measurement conditions were optimized. Dynamic swelling experiments at different pH agree very well with the expected fluorescence decrease for isotropic gels using overall volumetric data, despite the existence of internal gradients. Deviations are observed at large swelling degrees, provably due to protein-dye leakage, and at high protein concentrations. This simple and ubiquitous technique is used to spatially quantify the swelling of protein hydrogels in 2D at different swelling times, highlighting the existence of a variety of swelling profiles inside the gels with time.
      Graphical abstract image

      PubDate: 2016-10-30T12:06:27Z
       
 
 
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